Along with the popularity of wireless mobile communication networks, mobile terminal positioning techniques are more and more used in practice. The mobile terminal positioning techniques include satellite wireless positioning techniques and terrestrial wireless positioning techniques. Specifically, the satellite wireless positioning techniques may implement three-dimension mobile terminal positioning using the Global Positioning System (GPS), but the cost for the mobile terminal positioning is higher. The terrestrial wireless positioning techniques implement two-dimension mobile terminal positioning by measuring parameters such as the propagation time, the field intensity of signal, the phase, or the incident angle of a transmission signal or the like, the implementation is easy and the cost is lower. At present, the terrestrial wireless positioning techniques are usually used for positioning a mobile terminal.
Mobile terminal positioning implemented using the terrestrial wireless positioning techniques often uses the positioning method based on the wireless mobile communication network. That is, multiple base stations in the wireless mobile communication network control and measure the transmission signal between the mobile terminal and themselves simultaneously to obtain the parameter of the transmission signal, and positioning estimation is performed for the mobile terminal using a predetermined measurement algorithm. In such a mobile terminal positioning process, the accuracy of the mobile terminal positioning is determined by the accuracy of the obtained parameter of the transmission signal, and the propagation of the transmission signal highly depends on the channel characteristics of the wireless mobile communication network, thus the final accuracy of the mobile terminal positioning relies on the channel characteristics of the wireless mobile communication network.
Specifically, the mobile terminal positioning method using the terrestrial wireless positioning techniques may be a Time Difference of Arrival (TDOA) method. The TDOA method specifically includes the following. When positioning is performed for the mobile terminal, the serving base station that serves the mobile terminal obtains the transmission time of a positioning signal between the serving base station and the mobile terminal as well as between two base stations relatively near the mobile terminal and the mobile terminal respectively. Then, the serving base station performs calculation according to Math Figure 1 to obtain the position of the mobile terminal.
                    MathFigure        ⁢                                  ⁢        1                                                            {                                                                                                                                   (                                                                                                                                                                  (                                                                                                      x                                    0                                                                    -                                                                      x                                    2                                                                                                  )                                                            2                                                        +                                                                                          (                                                                                                      y                                    0                                                                    -                                                                      y                                    2                                                                                                  )                                                            2                                                                                                      -                                                                                                                                            (                                                                                                      x                                    0                                                                    -                                                                      x                                    1                                                                                                  )                                                            2                                                        +                                                                                          (                                                                                                      y                                    0                                                                    -                                                                      y                                    1                                                                                                  )                                                            2                                                                                                                          )                                        2                                    =                                      R                    21                    2                                                                                                                                                                  (                                                                                                                                                                  (                                                                                                      x                                    0                                                                    -                                                                      x                                    3                                                                                                  )                                                            2                                                        +                                                                                          (                                                                                                      y                                    0                                                                    -                                                                      y                                    3                                                                                                  )                                                            2                                                                                                      -                                                                                                                                            (                                                                                                      x                                    0                                                                    -                                                                      x                                    1                                                                                                  )                                                            2                                                        +                                                                                          (                                                                                                      y                                    0                                                                    -                                                                      y                                    1                                                                                                  )                                                            2                                                                                                                          )                                        2                                    =                                      R                    31                    2                                                                                                          [                  Math          .                                          ⁢          1                ]            
Specifically, the coordinates of the position of the mobile terminal are (x0, y0), the coordinates of the position of the serving base station are (x1, y1), and the coordinates of the position of the two base stations relatively near the mobile terminal are (x2, y2) and (x3, y3) respectively.R21=c×t21 andR31=c×t31,
where c is the propagation velocity of the positioning signal in the air, t21 represents a difference in the transmission time of the positioning signal between one of the relatively-near base stations and the serving base station, and t31 represents the difference in the transmission time of the positioning signal between the other relatively-near base station and the serving base station.
Here, there are two methods for the serving base station to obtain the transmission time of the positioning signal between the serving base station and the mobile terminal as well as between the two base stations relatively near the mobile terminal and the mobile terminal respectively. In the first method, the mobile terminal sends an uplink ranging signal, and after the serving base station and the two base stations relatively near the mobile terminal measure the transmission time required for receiving the uplink ranging signal, the two base stations relatively near the mobile terminal report the transmission time of the uplink ranging signal obtained by performing the measurement to the serving base station. In the second method, the serving base station instructs the serving base station and the two base stations relatively near the mobile terminal to send a downlink positioning signal to the mobile terminal respectively, and after measuring the transmission time required for receiving the downlink positioning signal respectively, the mobile terminal reports the same to the serving base station.